Prevalence and racial distribution of primary canine hypoplasia of the maxillary canine.

Primary canine hypoplasia (PCH) is an enamel defect located on the mesial aspect of the facial surface at approximately the junction of the gingival and the middle thirds of the tooth. 1-5 The defect exists in two forms: minimal hypoplasia consisting of brown, white, or yellow opaque areas with a smooth surface; and obvious hypoplasia having a combination of pitting, invagination, missing enamel, or a rough-textured surfaceo s In obvious hypoplasia, opaque areas may be present and there will be at least one other abnormality. Duncan et al. 4 examined the mandibular primary canines of 334 African-American 3to 5-year-old children, and found a prevalence of 37.1% for AfricanAmerican males and females, with no apparent differences between fluoridated and nonfluoridated communities. Twentylsix percent of the defects had an associated carious lesion. Silberman et al. 3 compared the data reported by Duncan et alo with that of 37 Caucasian children examined at two Head Start centers during the same study. The prevalence noted for the Caucasian children was 11%. Silberman et al. s examined 2686 randomly selected Mississippi school children, African-American and Caucasian, 4 and 8 years old, and found the prevalence rate of PCH on mandibular canines to be 33.2% for African-American children and 17.2% for Caucasian children. African-Americans had a significantly (P -0.0001) higher prevalence than Caucasians, and males a significantly (P = 0.01) higher prevalence than females. A significant (P = 0.001) relationship also was demonstrated between PCH and dental caries. Water fluoridation status, age, geographic location (urban or rural), and breast-feeding history were not related to PCH. Very little has been written about PCH in the maxillary canine. Brown and Smith6 examined all four primary canines of 112 children ages 3-10 years seen on recall visits and concluded that the mandibular teeth were affected twice as often as the maxillary. They also noted very little difference in prevalence between the maxillary canine and the left mandibular canine, but the prevalence of the right mandibular canine was remarkably higher. They did not address racial differences. A recent study7 of 113 school children of Harappa, Punjab Province, Pakistan, noted a prevalence of PCH of 34.5% with no significant association between the defect and gender, socioeconomic status, or side of the jaw. The defect occurred significantly more frequently in the mandible than in the maxilla. The purpose of this report is to provide prevalence data for PCH affecting the maxillary primary canines in different age, gender, and race cohorts.